I made a Trifield decoder a few months ago (with the help of Aaron Heller, to understand how to use Faust), and it works surprisingly well! The distances can be adjusted, so it would work with 3 speakers on a plane. The only problem is the patent... So I'm not sure I can distribute it.
-- Marc Tue, 8 Apr 2014 20:00:57 +0200, JQ Adams <jqad...@google.com> wrote : > Trifield is new to me. Thanks for this. > > I'm not entirely certain what is said in this article...: > > *Each filtered signal then passes to a sine/cosine potential divider, > which > > is set differently for each frequency band. Only with this > > arrangement, Gerzon found, could a wide stereo image and sharpened > > central focus be traded off effectively against one another across > > the entire audible spectrum.[image: Inline image 1]* > > > This seems to be saying that different weightings of energy gets sent > to the middle versus side speakers. I would presume the center > channel would receive the greater proportion of low frequency > content, but it's not said here, directly. > > Funny enough, I did have in mind to ask in followup whether the the > L/R speakers could effectively be just small tweeters, as my > understanding is for a person to decode direction, it's most > important that high frequency energy is reproduced well. Practically > (for me) it simplifies/reduces cost/is more discreet to have small > drivers added to the sides of monitors. I had not thought about a > need to reduce the high frequency energy to the center channel...but > in a way that sorta sounds reasonable... > > One further question I would pose is that of necessity of delays. In > my instantiation, the loudspeakers would all be on a plane (the front > wall), and thus for a centered listening position, the center > loudspeaker would be closer. Given that we may have a dual video > screen system, the perceived angle may be upwards of 90° for a > near-seated participant. Imagining this as a 45-45-90 right triangle > with the listener at the right angle, the loudspeakers would be on > the hypotenuse at distances of *s*, sqrt(2)/2**s*, *s* for left, > center, right. This would seem to indicate a delay on the center > channel that scales in magnitude with the size of the room. When *s* > is 3m, the distance variance would be about .88m, or about 2.5ms, > which I don't know whether is significant... > > > On Tue, Apr 8, 2014 at 7:06 PM, Paul Hodges > <pwh-surro...@cassland.org>wrote: > > > --On 08 April 2014 18:45 +0200 JQ Adams <jqad...@google.com> wrote: > > > > > My question pertains to play back to a three speaker setup (left, > > > center, right)...would it be most correct to send the 'mid' signal > > > directly to a center speaker and the 'side' signal to speakers > > > left and right, phase inverted from each other? > > > > Have you thought of Trifield as a possibility? > > > > < > > http://www.stereophile.com/content/upward-mobility-2-channels-surround-page-2 > > > > > > > Paul > > > > -- > > Paul Hodges > > > > > > _______________________________________________ > > Sursound mailing list > > Sursound@music.vt.edu > > https://mail.music.vt.edu/mailman/listinfo/sursound > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <https://mail.music.vt.edu/mailman/private/sursound/attachments/20140408/a0d76726/attachment.html> > -------------- next part -------------- A non-text attachment was > scrubbed... Name: image.png > Type: image/png > Size: 38014 bytes > Desc: not available > URL: > <https://mail.music.vt.edu/mailman/private/sursound/attachments/20140408/a0d76726/attachment.png> > _______________________________________________ Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/mailman/listinfo/sursound _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
